Wire spacer for a plate type heat exchanger, plate type heat exchanger provided with such a wire spacer, and method of upgrading a heat exchanger

ABSTRACT

A wire spacer ( 20 ) for spacing two adjacent heat transfer plates ( 2, 4 ) of a plate type heat exchanger ( 1 ). The wire spacer ( 20 ) is formed by a bent wire ( 22 ) that is alternatingly abutting the two adjacent heat transfer plates ( 2, 4 ), while extending along the fluid channel ( 6, 8 ) of the heat exchanger ( 1 ). The wire spacer ( 20 ) has first and second support segments ( 24, 26 ) providing a plate supporting function, and spacing segments ( 28 ) for maintaining a minimal vertical spacing (Δy) between the heat transfer plates ( 2, 4 ) during heat exchanger operation. The first lower support segments ( 24 ) are formed by wire paths ( 32 ) that span a plane (S 1 ) coinciding with a top surface of the lower heat transfer plate ( 2 ), and allow the wire spacer ( 20 ) to keep its orientation fixed with respect to the heat transfer plates.

TECHNICAL FIELD

The invention relates to a wire spacer for a plate type heat exchanger,and to a heat exchanger provided with a plurality of such wire spacers.Furthermore, the invention relates to a method for upgrading existingplate type heat exchangers.

BACKGROUND ART

A conventional plate type heat exchanger generally consists of aplurality of heat transfer plates, forming spatially separated butthermally connected fluid channels through which fluid streams with adifferent temperature are allowed to flow. This enables heat transfer totake place from the hotter fluid to the colder fluid.

From U.S. Pat. No. 2,595,457, various plate type heat exchangerconfigurations are known, having a heat exchanger plate assembly orplate core comprising heat transfer plates between which heat exchangerelements in the form of periodically (e.g. sinusoidally) bent wires aremounted. One function of these bent wires is to provide extended wirefin surfaces that increase the effective heat transfer area of the heattransfer plates. A second function of the bent wires is to maintain aparallel orientation of the adjacent heat transfer plates, so that thefluid channels will not deform as a result of the thermal gradientsoccurring during use. As shown in U.S. Pat. No. 2,595,457, theperiodically bent wire spacers generally comprise first support segments(e.g. a yoke portion of a U-shape) for abutting the first heat transferplate along a first support line in the direction of the fluid flow,second support segments (e.g. a yoke portion of an inverted U-shape) forabutting the second heat transfer plate along a second support line andat a spacing distance from the first support line, and spacing segments(e.g. legs of the U-shape) interconnecting the first support segmentsand the second support segments in an alternating manner.

The periodical wire spacers from U.S. Pat. No. 2,595,457 have to bewelded or brazed with their yoke portions to at least one of the heattransfer plates, in order to fix the orientation of the wire spacer withrespect to the plates, and to provide sufficient thermal bonding forobtaining the increased effective heat transfer area. The requiredwelding or brazing complicates manufacturing of such a heat exchanger.

SUMMARY OF INVENTION

It would be desirable to provide a wire spacer for a plate type heatexchanger, which simplifies heat exchanger construction and/ormaintenance.

Therefore, according to a first aspect, there is provided a wire spaceraccording to claim 1.

The wire spacer according to this aspect of the invention is formed bybending a stiff wire into a desired elongate shape. The mechanicalstiffness (or rigidity) of the wire material is sufficient to maintainthe predefined wire shape during use of the heat exchanger, to properlyspace (i.e. maintain the desired space between) the heat transferplates. The minimally required stiffness is determined by the alloweddeformations of the wire spacers and the heat transfer plates under thetypical thermal gradients and mechanical stresses occurring during heatexchanger operation. The wire portion perpendicular to the plates mustbe rigid with respect to the stresses imposed on the wire, and the wirethickness must be selected to meet this condition.

Typically, the heat transfer plates are 1-2 millimeter thick, so thatthe wire cross-section (or diameter, in case of a cylindrical wire)typically needs to be in the range of 2-4 millimeter. For such aconfiguration, height of the vertical portion must be 0.1 to 0.2 mmsmaller than the spacing distance between the heat transfer plates, bothin cold condition and during shop assembly, in order to accommodate thesmall deformation due to thermal gradients during operation.

The material of the wire should be selected based on the expected heatexchanger operating temperature and thermal gradient forces. Among thepossible wire materials are carbon steel wire (uncoated or aluminized orgalvanized), various grades of austenitic stainless steel. A circularwire cross-section is preferred, but other wire cross-section shapes(e.g. polygonal) are possible.

The wire paths jointly span the support plane parallel to and abuttingthe first (lower) heat transfer plate. “Spanning of the plane” refersherein to providing at least three points that are non-coinciding andnot co-linear, and that together define the support plane. The term“wire path” refers herein to a continuous portion of the bent wire thattraces out a curved or bent wire trajectory spanning at least a line butpreferably spanning a portion of the support plane (e.g. by forming asemi-circular shape, a U-shape, an S-shape, or a W-shape, within thesupport plane). In any case, the wire paths are formed to at leastjointly span the support plane comprising the first support line.

The first support line forms a path along the first heat transfer plate,which path may for example be linear along a first directioncorresponding to the main flow direction of the fluid within the channelenclosed by the adjacent heat transfer plates, e.g. in a cross-flowplate type heat exchanger with linear fluid channels. Alternatively, thefirst support line may be slightly curved, or even substantially curvedso as to follow a more sophisticated trajectory, e.g. the trajectorydefined by the curved fluid channels in a Z-type concurrent- orcounter-flow plate type heat exchanger.

Each wire path extends at its path ends into respective spacingsegments. The spacing segments interconnect the first support segmentsand the second support segments in an alternating manner, and have amechanical stiffness that is sufficiently large for keeping the firstand second heat transfer plates at the desired spacing distance, as wasdescribed herein above.

The co-planar shapes of the wire paths cooperate to form the supportplane, such that the wire spacer can be positioned between the heattransfer plates with this common support plane parallel to and abuttinga heat transfer surface of the first heat transfer plate. In theintended orientation, the spacing segments fix the orientation of thesecond support segments at the desired spacing distance with respect tothe base wire portions and the support plane. So effectively, each wirepath in the wire spacer according to this aspect of the inventionfunctions as a base for supporting the wire spacer, and for fixing theorientation of the wire spacer with respect to the heat transfer plates.

According to embodiments of the wire spacer, the spacing segments extendat least partially and preferably entirely along a second direction thatis locally perpendicular to the first support line.

In case of a straight first support line, the second direction isperpendicular to the first direction. For adjacent parallel heattransfer plates, this second direction will be perpendicular to the heattransfer surfaces of both heat transfer plates.

In general, the proposed wire spacer according to this aspect allows foreasy placement between two adjacent heat transfer plates, withoutneeding further means for holding the wire spacer in the correctionupright orientation.

The proposed wire spacers may be configured as relatively thin elongatedstructures, which do not occupy a significant volume. In contrast tothis, bar spacers (e.g. known from patent document U.S. Pat. No.5,383,516) occupy a larger volume, significantly reduce the effectivecross-section of the fluid channels, and undergo substantialdifferential thermal expansion and thermal stresses during heatexchanger operation. Similarly, plate-embossing spacers (e.g. known frompatent document U.S. Pat. No. 2,281,754) create large flow obstructionsand corresponding pressure drops.

According to an embodiment, the wire paths of the wire spacer jointlyextend bi-directionally from the first support line and along atransversal direction, which is perpendicular to the first support lineand is within in the support plane.

According to further embodiments, the wire paths may comprise smoothlycurved portions and/or connected linear segments, or various othershapes spanning the support plane. For example, any of the wire pathsmay comprise interconnected linear path segments that are oriented inthe support plane and perpendicular to the first support line.Alternatively, any wire path may be formed as a smoothly curved shapewith its curvature spanning the support plane, e.g. a semi-circular wirepath.

According to an embodiment, each wire path extends to at least one sideof the first support line along the transversal direction, which isoriented perpendicular to the first support line. The wire paths mayextend toward opposite sides in an alternating manner along the wirespacer. For example, one particular wire path may extend to the positivetransversal direction, while the preceding and subsequent wire pathsextend to the negative (i.e. opposite) transversal direction. Thisalternating configuration allows fixing the orientation of the wirespacer between the heat transfer plates, while requiring a minimalamount of wire.

According to a further embodiment, each wire path may be individuallybent to extend bi-directionally along both the positive and negativetransversal directions from the first support line, to span a total basewidth.

A wire path that by itself extends to both directions from the firstsupport line allows stabilization of its orientation with respect to thefirst heat transfer plate. Furthermore, if each wire path is identicallyshaped to extend in both transversal directions, then the wire spacermay be formed as a periodical structure of consecutive identical unitsthat each comprise an interconnected quadruplet formed by a firstsupport segment, a spacing segment, a second support segment, and afurther spacing segment. This periodicity greatly simplifies themanufacturing process wherein the wire is bent to form the proposed wirespacer.

According to a further embodiment, the total base width equals thespacing distance.

If the total base width equals the spacing distance, then an incidentaloccurrence of local twisting of the wire spacer about an axis parallelto the support line (i.e. a rotation of wire paths in the plane spannedby the spacing direction and transversal direction) will not have adetrimental effect on the spacing function. At the site of the twisting,the rotated wire paths with a total base width matching the desiredspacing distance will still locally provide a spacing function.

According to an embodiment, the wire path may be formed by multipleinterconnected linear path segments that are arranged with their longaxes directed along the transversal direction. These linear pathsegments may be abutting as viewed along the support line, andinterconnected by short curved portions at the respective segment endpoints. In this configuration, a length of the wire path viewed alongthe support line (i.e. the first or fluid flow direction) can beminimized, while the support width in the transversal direction will bemaximized. Hence, stabilization in the spacing direction and transversaldirection is optimized, while an effective thermal contact area betweenthe wire spacer and the heat transfer plate is kept relatively small.

For example, the wire path may be formed as one of a contracted U-shape,a contracted S-shape, or a contracted W-shape. Any one of these shapesis easily formed in a manufacturing process involving wire bendingactions in the positive and negative transversal directions only. Hence,wire bending actions in the direction along the support line, whichcomplicate the manufacturing process, are avoided.

According to another embodiment, the wire path is smoothly curved in thesupport plane. According to further embodiments, the wire path forms oneof a U-shape, an S-shape, or a curved W-shape.

A smoothly curved wire path is easily formed by bending the wire intothe desired shape, without creating sharp turns or folds. Smooth curvesminimize the risk of breaking the wire during construction. The smoothlycurved wire path provides a considerable structural support area in thesupport plane, while minimizing the thermal contact area between thewire spacer and the first heat transfer plate. Any one of a smoothlycurved U-shape, an S-shape, or a curved W-shape, is easily formed in amanufacturing process involving wire bending actions in the transversaldirections only. Hence, wire bending actions in the direction along thefirst support line, which would complicate the manufacturing process,are avoided.

According to an embodiment, the second support segments are formed bylinear support segments with support lengths along the first supportline.

The first support segments are effectively spaced along the firstsupport line by the linear support segments. The preferred lengths ofthese linear support segments are determined by the expecteddifferential pressures between the adjacent channels and the operatingtemperatures occurring in the heat exchanger. In particular, by formingthe support segments with equal lengths, the wire spacer possesses alinear symmetry that will provide a nearly uniform linear supportingcapability along the first support line. Correspondingly, the wirespacer manufacturing process is greatly simplified.

According to a further embodiment, the support lengths are equal supportlengths in the range of 100 mm-200 mm.

Support lengths in the range of 100 mm-200 millimeter allow robustspacing in a heat exchanger having heat transfer plates of 1-2millimeter thickness, and operating at a differential pressure of500-1000 Pa in a temperature range of 100-300 C.

According to an embodiment, the spacing segments are formed byperpendicular linear segments with spacing heights equal to the spacingdistance. Optionally, the wire could extend transversely at the end ofthe perpendicular linear segments in addition to or in alternative tosupport segments along the first support line.

Spacing segments formed from linear segments that are oriented along thespacing direction provide maximal structural integrity and support.

According to an embodiment, a cross-section of the bent wire iscircular.

A circular wire is easy and cheap to construct. Due to its cylindricalsymmetry, the circular wire is easily bent into any desired elongatedwire spacer shape. In addition, the isotropic bending resistance of thecircular wire allows bending in the transversal and spacing directionsrequired for forming the inherently three-dimensional configuration ofthe proposed wire spacer according to the first aspect. The circularcross section also minimizes the contact area between the wire spacerand the heat transfer plates, thereby avoiding excessive thermalgradients and resulting stresses occurring during operation of the heatexchanger (as is the case with pins or stud spacers welded to heattransfer plates, e.g. known from patent document WO96/19708).Furthermore, any thermal insulation coating can be applied to the smoothsurface of the circular wire spacer in an easy and durable manner.

According to a further embodiment, a wire diameter of the bent wire isin a diameter range of 2-4 mm.

At the expected heat exchanger design temperatures and thermal gradientforces described herein above, this preferred diameter range yields awire spacer that is sufficiently rigid to prevent deformation, whilestill allowing the wire to be manufactured without difficulty. A thickerwire would be difficult to process, while a thinner wire would not beable to prevent deformation.

According to an embodiment, the bent wire has a first end and a secondend, wherein each end is provided with attachment means for connectingthe wire spacer to the first heat transfer plate and/or the second heattransfer plate. Optionally, this connection could be through electricalresistance welding or through a pin welded to the first and/or secondheat transfer plates.

By providing the wire spacer with attachment means at the opposite wireends, the wire spacer may be easily fixed with respect to the heatexchanger by attachment to externally accessible regions of the heatexchanger, for example to the plate edges near fluid channel apertures,or to flow guiding elements (ferrules) located at the plate edges.

According to a second aspect, and with corresponding effects andadvantages as described herein above, there is provided a plate typeheat exchanger as defined by claim 10.

As described herein above with respect to the first aspect of theinvention, the first direction corresponding to the main flow directionof the fluid within the channel enclosed by the adjacent heat transferplates may define a straight first support line along the first heattransfer plate (like in a cross-flow plate type heat exchanger withlinear fluid channels). Alternatively, this first direction may also beconstrued as a local direction, which may change along the first supportline. This allows the first support line to be curved along the fluidchannel of the heat transfer plate (like in curved fluid channels in aZ-type concurrent- or counter-flow plate type heat exchanger).

According to an embodiment, the at least one wire spacer of the platetype heat exchanger is releasably positioned between the adjacent heattransfer plates, and wherein the first end and second end of the wirespacer are fixed to respective outer edges of the heat transfer plates.Optionally, this attachment can be made by electrical resistance weldingor by welding a pin to the heat transfer plates.

According to a third aspect of the invention, there is provided a methodfor upgrading an existing plate type heat exchanger as defined by claim14.

The effects and advantages of a heat exchanger resulting from theupgrading method according to this aspect have already been describedherein above in view of the other aspects. In addition to a method forupgrading an existing heat exchanger, the method according to thisaspect may also represent the reassembly phase after cleaning orrepairing any heat exchanger provided with the wire spacers according tothe first aspect of the invention. In such cleaning or repairingmethods, the initial phase comprises removing the wire spacers from thefluid channels of the plate type heat exchanger. Subsequently, the heattransfer plates having the wire spacers removed are easily cleaned orrepaired by suitable methods without obstruction from the wire spacers.Subsequently, the original wire spacers or repaired substitutes arere-inserted into the fluid channels, as defined by this third aspect ofthe invention.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying schematic drawings in which correspondingreference symbols indicate corresponding parts, and in which:

FIG. 1 schematically shows a heat exchanger according to an embodiment,and

FIG. 2a-2d present perspective views of wire spacers according toembodiments;

The figures are meant for illustrative purposes only, and do not serveas restriction of the scope or the protection as laid down by theclaims.

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a perspective view of a plate type heat exchanger 1 forexchanging thermal energy between a first fluid 14 and a second fluid 16having a different temperature. The shown heat exchanger 1 comprises anumber of stacked heat transfer plates 2, 4. Between each two adjacentheat transfer plates 2, 4 first fluid channels 6 and second fluidchannels 8 are formed, for transporting the first fluid 14 and secondfluid 16 respectively.

The first and second fluid channels 6, 8 are oriented mutuallyperpendicular, along a first direction X and a transversal direction Zrespectively. The first and second fluid channels 6, 8 are alternatinglyprovided in the heat exchanger 1 in a second (vertical) direction Y,which is perpendicular to the first direction X and the transversaldirection Z. This plate configuration forms a so-called cross flow platetype heat exchanger. The adjacent heat transfer plates 2, 4 are spacedapart at a spacing height Δy in the second direction Y. Several of thefirst fluid channels 6 are provided with a plurality of wire spacers 20.The shown wire spacers 20 comprise first support segments 24, secondsupport segments 26, and spacing segments 28 that interconnect the firstsupport segments 24 and the second support segments 26.

The first support segments 24 are formed so as to abut the first heattransfer plate 2 along a first support line C1, and the second supportsegments 26 are formed so as to abut the second heat transfer plate 4along a second support line C2.

The first support segments 24 are curved into wire paths 32, whichjointly define a first support plane S1 that comprises the first supportline C1. As shown in FIG. 1 and further illustrated by FIG. 2 a, eachwire path 32 comprises three linear path segments 34 a-c that areinterconnected via sharply curved segments, jointly forming a contractedS-shape. As a result, the linear path segments 34 a-c of each wire path32 jointly extend bidirectionally from the first support line C1, andspan the first support plane S1 along both the first support line C1 anda transversal direction Z. Consequently, each wire path 32 forms asupport portion that spans a total base width Δx and effectively holdsthe wire spacer 20 steady between the heat transfer plates 2, 4, withthe spacing wire segments 28 in an upright orientation. Preferably, thetotal base widths Δx of the wire paths 32 equal the spacing distance Δybetween the second support segments 26 and the first support line C1.

The second support segments 26 are formed as linear wire segments withsecond support lengths Δx2 along the second support line C2. Here, thesecond support lengths Δx2 of subsequent second support segments 26 areshown to be equal. A typical value for the second support lengths Δx2may be in the range of 100 mm-200 mm.

The spacing segments 28 interconnect the first support segments 24 andthe second support segments 26 in an alternating manner. The spacingsegments 28 in the shown embodiments are formed as linear wire segmentsthat are perpendicular to the first support plane S1, and which hold thesecond support segments 26 at a spacing distance Ay from the firstsupport line C1. For a steel heat transfer plates of 1-2 mm thickness,the spacing distance Δy is preferably 0.1 to 0.2 mm smaller than a platedistance between the heat transfer plates 2, 4 of a fluid channel 6, 8in cold condition.

The wire spacer 20 is manufactured from bending a wire 22 having acircular cross-section, into a periodical structure having amultiplicity of the described segments. A typical wire diameter Ø of thebent wire 22 (see FIG. 2a ) is in a diameter range of 2-4 mm.

FIG. 1 shows that each bent wire 22 has a first wire end 6 located atone side of the first fluid channel 6. At this first wire end 6, thebent wire 22 is provided with attachment means 44 for connecting thewire spacer 20 to the first heat transfer plate 2. At the opposing sideof the first fluid channel 6, the wire spacer 20 terminates in a secondend (not shown), wherein also the second end is provided with similarplate attachment means 44. The wire spacers 20 are releasably positionedbetween the adjacent heat transfer plates 2, 4, by temporarily fixingeach wire spacer 20 with its first and second ends via the attachmentmeans 44 to respective outer edges of the first heat transfer plate 2.Alternatively, the attachment means 44 may also be provided on anupwardly bent portion of the wire spacer 20, so as to attach the wirespacer 20 to the second heat transfer plate (4). The attachment means 44can include ends of wire being attached through electrical resistancewelding or through a pin welded to the heat transfer plate 2 and/or 4.

In an alternative embodiment shown in FIG. 2 b, each wire path 32comprises only two linear path segments 34 a, 34 b that isinterconnected via one sharply curved segment, and which jointly form acontracted U-shape. Here, each wire path 32 only extends in a singletransversal direction Z within the first support plane Si from the firstsupport line C1. Consecutive wire paths 32, 32′ transversally extend inopposite transversal directions, so that the wire paths 32 jointlyextend bidirectionally from the first support line C1.

Many alternative wire spacers 20 provided with wire paths 32 formed fromlinear path segments and sharply curved connection segments may beconceived. For example, the wire path 32 may be formed from a contractedW-shape with four linear path segments joined by three sharply curvedinterconnection segments.

FIG. 2c shows an alternative embodiment of the wire spacer 20, whereinthe wire paths 32 are smoothly curved within the support plane S1, so asto form a smooth S-shape. Also in this embodiment, each wire path 32extends bi-directionally from the first support line C1, and spans atotal base width Δz. The wire spacer 20 in FIG. 2c has a smoothly curvedfirst support segment 24 with a first support length Δx1 that isconsiderably larger than in the previous embodiments.

Many alternative embodiments provided smoothly shaped wire paths 32 maybe conceived. For example, the wire path 32 may be formed as a U-shape,or a curved W-shape.

FIG. 2d shows a further alternative embodiment of wire spacer 20,wherein each wire path 32 comprises three linear path segments 34 a-cthat are interconnected via sharply curved segments, jointly forming acontracted S-shape, similar to the embodiment shown in FIG. 2A. However,in FIG. 2d , wire path 32 alternatingly forms first support segments 24along line C1 and C2, with second support segments 26 and spacingsegments 28 between.

Any of the wire paths 32 described above have the property that wirespacer 20 is formed by bending the wire 22 using only bending operationsin directions transversal to a main direction along the wire spacer 20,e.g. along the first direction X (or any of the support lines C1, C2).

Alternatively, the wire path 32 may also be formed from backward orforward wire bending operations along this main direction along the wirespacer 20, although this will complicate the manufacturing process. Bysuch a process, a wire spacer 20 having a more complex wire path 32configuration may be obtained. An example of such a complex wire path 32is a (nearly) circular wire path (not shown) that starts at an end of aspacing wire 28, extends perpendicular along the transversal directionZ, curves backward along the negative first direction −X, toward thenegative transversal direction −Z, toward the positive first directionX, and back along the transversal direction Z to extend into asubsequent spacing wire.

The descriptions above are intended to be illustrative, not limiting. Itwill be apparent to the person skilled in the art that alternative andequivalent embodiments of the invention can be conceived and reduced topractice, without departing from the scope of the claims set out below.

For example, any combination of the wire paths 32 described above may beprovided within a single wire spacer 20.

LIST OF REFERENCE SYMBOLS

-   1 plate type heat exchanger-   2 first heat transfer plate-   4 second heat transfer plate-   6 first fluid channel-   8 second fluid channel-   10 first fluid aperture-   12 second fluid aperture-   14 first fluid-   16 second fluid-   18 plate edge-   20 wire spacer-   22 bent wire-   24 first support segment-   26 second support segment-   28 spacing wire segment-   30 base wire portion-   32 wire path-   34 a-c linear path segment-   40 first end-   42 second end-   44 wire spacer attachment means-   Ø wire diameter-   X first direction-   Y second direction-   Z transversal direction-   S1 first support plane-   S2 second support plane-   C1 first support line-   C2 second support line-   Δx1 first support length-   Δx2 second support length-   Δy spacing distance-   Δz base width

1-13. (canceled)
 14. A wire spacer for spacing a first heat transferplate and a second heat transfer plate in a plate type heat exchanger,wherein the wire spacer comprises a bent wire comprising: first supportsegments for abutting the first heat transfer plate along a firstsupport line; second support segments for abutting the second heattransfer plate along a second support line; spacing segmentsinterconnecting the first support segments and the second supportsegments in an alternating manner, and spacing the second supportsegments at a spacing distance from the first support line; wherein thefirst support segments are bent into wire paths that jointly define asupport plane comprising the first support line.
 15. The wire spaceraccording to claim 1, wherein the wire paths jointly extendbi-directionally from the first support line and along a transversaldirection perpendicular to the first support line and within in thesupport plane.
 16. The wire spacer according to claim 2, wherein eachwire path extends in positive and negative transversal directions fromthe first support line.
 17. The wire spacer according to claim 3,wherein each wire path spans a total base width that equals the spacingdistance.
 18. The wire spacer according to claim 1, wherein the wirepaths are identically shaped, and wherein the wire spacer is formed as astructure of consecutive identical units that has periodicity along afirst direction parallel with the first support line.
 19. The wirespacer according to claim 5, wherein each unit comprises a sequence ofinterconnected segments formed by a first support segment, a spacingsegment, a second support segment, and a further spacing segment. 20.The wire spacer according to claim 1, wherein the wire path comprisesconnected linear path segments along the transversal direction, andpreferably forms one of a contracted U-shape, a contracted S-shape, or acontracted W-shape.
 21. The wire spacer according to claim 1, whereinthe wire path is smoothly curved in the support plane, and preferablyforms one of a U-shape, an S-shape, or a curved W-shape.
 22. The wirespacer according to claim 1, wherein the second support segments areformed by linear support segments with support lengths along the secondsupport line, preferably wherein the support lengths are equal supportlengths in the range of 100 millimeters to 200 millimeters.
 23. The wirespacer according to claim 1, wherein the spacing segments are formed byperpendicular linear segments with spacing heights equal to the spacingdistance.
 24. The wire spacer according to claim 1, wherein the wirepath extend bi-directionally from the second support line and along atransversal direction perpendicular to the second support line.
 25. Thewire spacer according to claim 1, wherein a cross-section of the bentwire is circular, and in particular wherein a wire diameter of the bentwire is in a diameter range of 2 millimeters to 4 millimeters.
 26. Thewire spacer according to claim 1, wherein the bent wire has a first endand a second end, wherein each end is provided with attachment membersfor connecting the wire spacer to the first heat transfer plate and/orthe second heat transfer plate.
 27. A plate type heat exchanger forexchanging thermal energy between two fluids, and comprising twoadjacent heat transfer plates forming a fluid channel along a firstdirection, and spaced apart at a spacing height in a second direction,wherein the plate type heat exchanger comprises at least one wire spaceraccording to claim 1 arranged between the two adjacent heat transferplates.
 28. The plate type heat exchanger according to claim 14, whereinthe at least one wire spacer is releasably positioned between theadjacent heat transfer plates, and wherein the first end and second endof the wire spacer are fixed to respective outer edges of the heattransfer plates.
 29. A method for upgrading an existing plate type heatexchanger for exchanging thermal energy between two fluids, andcomprising two adjacent heat transfer plates forming a fluid channelalong a first direction, and spaced apart at a spacing height in asecond direction, the method comprising: inserting at least one wirespacer according to claim 1 between the two adjacent heat transferplates; positioning the wire paths of the first support segments in amanner abutting the first heat transfer plate along a first support linein the first direction, and positioning the second support segments in amanner abutting the second heat transfer plate along a second supportline at a spacing distance from the first support line, thereby spacingthe adjacent heat transfer plates.